A continuation of the in vivo intracellular recording and labeling study of the dorsal (DCN) and posteroventral cochlear nuclei (PVCN) is proposed. After conducting a series of extracellular single-unit and two-electrode studies in both the barbiturate anesthetized and unanesthetized decerebrate gerbil, a database of response types for gerbil has been established. Two new, substantial physiological classes based on responses to noise have been discovered. Intracellular responses of cochlear nucleus projection neurons and interneurons to both acoustic stimulation and current- pulse injection through the recording electrode have been recorded. Identification of these neurons using neurobiotin as the cellular marker has resulted in an increase of recovered neurons compared to HRP. We need to continue this work in DCN and expand it to the PVCN, where we propose to identify the neurons that project form the PVCN to the DCN and elucidate their acoustic response properties. In order to understand the relationships between the response properties of units recorded in the decerebrate versus the barbiturate anesthetized preparation, we propose to study the effects of an ultrashort acting barbiturate on the acoustic responses of units recorded in the DCN of decerebrate preparations.